Apparatus for producing metal powder



Mal'h 2, l967 B. G. WINSTROM APPARATUS FOR PRODUCING METAL POWDER 5Sheets-Sheet l Filed July 14, 1964 INVENTOR.

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BERTL G. WH'STROM NRUS @n STARK E United States Patent Otitice PatentedMai". 2i, 1967 3,309,733 APPARATUS FOR PRODUCING METAL POWDER Berti] G.Winstrom, Mequon, Wis., assigner to A. 0. Smith Corporation, Milwaukee,Wis., a corporation of New York Filed July 14, 1964, Ser. No. 382,526 5Claims. (Cl. 18-2.5)

This application relates to an apparatus for producing metal powder andmore particularly to an atomizing nozzle assembly for producing finelydivided metal powder for use in powder metallurgy processes.

One common method of producing powdered metal, such as iron powder, isby a water atomization process. In a process of this type, a stream ofmolten metal is engaged by a high-pressure sheet of water which servesto atomize or disintegrate the strea-m of molten metal and producefinely divided particles.

The present invention is directed to an improved nozzle assembly for usein a water atomization process for forming metal powder.

According to the invention, the nozzle assembly includes a pair ofspaced Water nozzles which are in the form of elongated, generallycylindrical bars. Each nozzle bar is provided with an outlet slotthrough which the water is directed toward the molten metal streampassing between the nozzle bars. The nozzle assembly contains watermanifolds or passages which communicates with the slots in the nozzlebars so that water is continuously discharged through the outlet slotsagainst the stream of molten metal in the form of oppositely directedstreams or curtains.

In order to adjust the angle at which the water sheets are directed atthe molten metal stream, each nozzle bar is mounted for rotation withina socket formed in the nozzle assembly. By rotating the nozzle bar, theposition of the outlet slots with relation to the stream of metal can bechanged to thereby vary the angle at which the sheets of water impingedagainst the molten metal stream.

The nozzle assembly of the present invention produces clean, sharpsheets of water which provide a more effective atomization ordisintegration of the molten metal into powdered or particulate form. Inaddition, the design of the nozzle discharge slots and the supplymanifolds minimizes the pressure loss through the nozzle assembly whichagain aids in producing a more effective atomization.

As the cylindrical nozzle bars are rotatable within the nozzle assembly,the angularity of the water sheets can be adjusted with relation to thestream of molten metal so that the most effective angle of engagementcan be selected, with the desired angle depending on the thickness ofthe molten metal stream, the temperature of the molten metal and thecomposition of the metal. As an added feature, an indicating device isprovided on the nozzle assembly which gives a visual indication of theangle at which each water sheet is engaging the molten metal stream.

Other objects and advantages will appear in the course of the followingdescription.

The drawings illustrate the best mode presently contemplated of carryingout the invention.

In the drawings:

FIG. l is a schematic representation of the apparatus for producingmetal powder;

FIG. 2 is a plan View of the atomizing nozzle assembly with parts brokenaway in section;

FIG. 3 is a side elevation of the nozzle assembly with parts broken awayin section;

FIG. 4 is a plan view of the body of the nozzle assembly with partsbroken away in section;

FIG. 5 is an enlarged fragmentary elevation of a nozzel bar; and

FIG. 6 is a transverse section of the cylindrical nozzie bar.

The drawings illustrate an apparatus for producing metal powder, whichcomprises a tundish 1 adapted to contain a molten metal 2, suc-h asiron, steel, stainless steel, copper, or the like. The lower surface ofthe tundish 1 is provided with two rows of orifices 3 and the moltenmetal flows downwardly by gravity through the orifices in a series ot'streams 4.

The streams 4 of molten metal pass downwardly through openings in anozzle assembly 5 and water sheets are directed against the molten metalstreams by the nozzel assembly to atomize or disintegrate the moltenmetal into tine particles or powder which is collected in a container 6located beneath the nozzle assembly 5.

The nozzle assembly 5 includes a generally rectangular body 7 providedwith a series of lugs 8 which are connected by bolts to a supportingstructure 9 which serves to support the nozzle assembly beneath thetundish 1.

The upper end of the body 7 is enclosed by a head 10 and the head issecured to the body by a series of rows of bolts 11 which extendupwardly through aligned openings in the body and head. The outer rowsof bolts 11 are threaded into the head it? while the ybolts of thecentral yrow are threaded into bars 12 located within recesses 13 formedin the upper surface of the head 1t). The bars 12 are recessed so thatthe bolts 11 do not extend upwardly above the head 10. This enables thenozzle assembly to be located closely beneath the tundish 1 and allowsthe tundish, which contains the molten metal 2, to be moved freelyacross the top of the nozzle assembly.

According to the invention, the nozzle assembly includes a series ofgenerally cylindrical nozzle bars 14 which are mounted for rotationwithin sockets 15 formed in the head 1t). The nozzle bars 14 arearranged in pairs and are adapted 'to discharge oppositely directedsheets of water against the streams 4 of molten metal which are passingdownwardly between the nozzle bars 14 of each pair.

As best shown in FiG. 6, each nozzle bar 14 includes an elongated outletslot 16 through which the water is discharged toward the streams 4 ofmolten metal. The walls bordering the outlet slot 16 are generallyparallel and the inner end of the slot 16 communicates with a generallytapered middle slot Section 17. The inner end of the middle slot section17 communicates with an inner slot section 15, and the walls of bar 1-defining Slot section 18 are generally parallel so that thecrosssectional area of slot section 13 is substantially uniform. Theinner slot section 18 has a substantially greater width than thedischarge slot 16 and the walls of the tapered slot section 17 divergeinwardly at an angle A in the range of about 5 to 70 and generally about60.

Water is introduced into the inner slot section 18 through an elongatedrecess 19, and the recess extends circurnferentially through a sector ofabout 80 to 120 and generally about 9G", as shown by B in FiG. 6.

As best shown in FiG. 6, slot sections i6, 17- and 18 and the recess 19extend over a substantial portion of the length of the nozzle bar 14,and the end portions of the nozzle bar are solid and do not contain theslots or recess.

Water is supplied to the recess 19 of each nozzle bar 14 through aseries of generally vertical openings 20 in head 1?. The openings, asbest shown in FG. 2, are in aligned spaced relation and the lower end ofeach of the openings 2i) communicates with a vertical passage 21 in thebody 7 of the nozzle assembly. To seal the joint between the body 7 andhead 10, a generally oval seal 22 is located within a recess formed inthe upper surface of the body 7 and the seal extends around the openings20 and passages 21.

The lower ends of the passages 21 communicate with a cross passage 23and the ends of the cross passage are connected with longitudinallyextending manifolds 24. One end of each manifold is open and a supplyconduit 25 is connected to the open end of each manifold. Water,introduced into each manifold 24 through the supply conduits 25, flowstransversely through the cross passages 23 and then upwardly through thepassages 21 and openings 20 to the recesses 19 in the nozzle bars 14.

By introducing water into both of the manifolds 24, the pressure of thewater being discharged from the nozzle bars 14 can be increased withgiven pumping equipment. It is contemplatedy however, that under certaincircumstances, the water can be supplied through a single manifold 24,if desired.

The nozzle bars 14 are adapted to be rotated about their axes within thesockets 15 in order to adjust the angularity of the water sheet 34 beingdischarged through the outlet slots 16 with respect to the verticalstreams 4 of molten metal. To rotate the nozzle bars, the ends of eachnozzle bar 14 are provided with slots or notches 26, and a ridge 27 ofan indicator plate 28 is received within the notches 26. The indicatorplates 28 are located on the outer surface of the head 10 and each plate28 includes a pointer 29 which is adapted to be moved along a calibratedscale or dial 3Q having graduations of angularity of the dischargeopenings 16. The indicator plate 2S and the attached nozzle bar 14 canbe rotated until the pointer 29 is at the desired angle setting.

The indicator plates 2S can be locked to the head 10 by bolts 31 whichextend through the arcuate slots 32 in the indicator plate and arethreaded within openings in the head 10. After the indicator plate 23and the nozzle bar 14 have been rotated to provide the desiredangularity, the bolts 31 are threaded down so that the heads of thebolts engage the indicator plate 28 and loci; the plate and the nozzlebar in the desired position.

The molten metal 2 contained in the tundish 1 flows downwardly throughthe orices 3 in two rows of streams 4. The nozzle assembly is located`immediately beneath the tundish and the molten metal streams passdownwardly through openings 33 in the nozzle assembly. Pairs of nozzlebars 14 are located on either side of each opening 33 and sheets 34 orcurtains of water are discharged through the outlet slots 16 in thenozzle bars 14 and engage the molten metal streams. The force of thewater, which is generally at a pressure above 500 p.s.i. and usuallyabove 1,000 p.s.i., serves to atomize or disintegrate the molten metalstream to provide tinelydivided particles or powder which fallsdownwardly and is collected within the container 6.

To prevent oxidation of the molten metal stream 4 as it ows from thetundish 1 to the nozzle assembly, a shield 35 is positioned around eachrow of orifices 3 and extends from the lower surface of the tundish tothe nozzle assembly. A reducing gas such as hydrogen, carbon monoxide orthe like is introduced into each shield through a supply conduit 36. Thegas ows downwardly through the openings 33 and serves to shield themolten streams 4 as well as the metal powder produced from the streams 4from oxidation.

The container 6, in which the metal powder is collected, issubstantially lled with water, and the water level is maintained withinclose proximity to the nozzle assembly 5 so that oxidation of the metalpowder by exposure to the atmosphere is minimized. There is a certainamount of back splashing as the red hot powder contacts the water. andthe water level should be adjusted so that the 4 back splashing will notinterfere with the atomization of the metal stream.

To prevent the metal powder from piling beneath the nozzle, an inclinedramp 37 is positioned beneath each row of Vmetal streams 4 and thepowder will be deected laterally by the ramps 37 to the side portions ofthe container 6. The metal powder entering the water in container 6 isglowing red and tends to chunk-up or weld together. The ramps 37 serveto keep the powder in motion in the water and prevent settling of thepowder until the powder loses its red heat. Thus, the powder will notweld together and remains, generally, in a loose form.

The nozzle construction of the present invention provides a sharp, cleansheet of water which aids in the atomization of the molten metal. Theparticular shape of the slot sections 16, 17 and 18 in the nozzle bar 14insures that the stream of water being discharged will remain thin andwill not diverge as its emerges from the nozzle bar. More specifically,the inner slot section 1S has parallel walls and merges into the slotsection 17 which in turn leads into the narrow outer slot section 16having parallel walls. This construction enables the water to bedischarged with a minimum pressure loss and in a thin, clean sheet.

As the nozzle bars 14 are mounted for rotation in the sockets 15, theangularity of the water sheets being dischargedY through the slots 16can be readily changed without making any change in the waterconnections or piping within the nozzle assembly. Each nozzle bar 14 canbe individually adjusted so that the opposed water sheets can eitherhave the same angularity or a different angularity as desired. Inaddition, each nozzle bar is provided with an indicator which gives avisual indication of the angle at which the Water is being dischargedthrough the nozzle 16, and this enables the operator to readily changeor adjust the angularity without calibration or measurement.

Various modes of carrying out the invention are contemplated as beingwithin the scope of the following claims particularly pointing out anddistinctly claiming the subject matter which is regarded as theinvention.

I claim:

1. Apparatus for producing metal powder, which comprises a container forholding molten metal and having an opening therein for discharge ofmolten metal therefrom, a nozzle assembly disposed adjacent to thecontainer and having a nozzle provided from an elongated solid bar, saidnozzle bar having a longitudinally elongated slot extending through thenozzle bar generally centrally Of the length of said bar from one sideof the peripheral surface of the nozzle bar to the other, said slothaving an inlet section and an intermediate section, and an outletsection disposed toward the stream of molten metal with the walls of thenozzle bar defining the inlet section being generally parallel andhaving greater width therebetween than the walls of the bar defining theoutlet section of the slot, the walls of the outlet section also beinggenerally parallel to each other, and the walls of the bar detining theintermediate section tapering from a greater width therebetween adjacentthe inlet section to a lesser width at the outlet section to provide forgradual constriction of the fluid owing through the nozzle bar to theoutlet section for discharge therefrom in sheet-like form, liquid supplyconduit means connected to the inlet section of the nozzle bar to supplyliquid to the inlet section of the nozzle bar under substantially highpressure for ow therethrough and discharge from the outlet sect1onagainst the molten metal to atomize the latter, means engaging thenozzle bar to prevent deection and lateral enlargement of the slot dueto the internal pressure of the liquid passing through the slot, andmeans to support the nozzle assembly adjacent to the container.

2: The apparatus of claim 1 in which the means engagmg the nozzle barfor preventing deflection is dis posed in engagement with the peripheralsurface of the nozzle bar and extends yover a substantial portion ofsaid surface and for a substantial portion of the length of the nozzlebar to provide an elongated socket for receipt of the nozzle bar.

3. The apparatus of claim 1 in which the liquid supply conduit meansincludes a series of separate liquid supply passages which communicatewith the inlet section of the slot at spaced locations along the lengthof the slot.

4. The apparatus of claim 1 in which the nozzle assembly includes anelongated socket to rotatably receive the nozzle bar, and means torotate tbe nozzle bar in the socket to locate the outlet section of theslot at different angular positions for varying the angularity of tbesheetlike discharge of liquid with respect to the stream of moltenmetal.

5. The apparatus of claim 4, and means for selectively holding thenozzle against rotation at a predetermined angle, and indicator meansfor visually indicating the angularity of the slot With respect to thestream of molten metal.

References Cited by the Examiner UNITED STATES PATENTS Neil 18-2.5Williams et al 18-2.5

White 239-597 X Lennox 18-2 X Roberts et al 264-12 X Probst et `al18-2.5 Monson et al. 264-12 Roberson 65-5 Shrewsbury 239-597 X Denniston18-2.5 X Millet 65-5 Gre at Britain.

9/1906 Great Britain. 6/1950 Great Britain.

WILLIAM I. STEPHENSON, Primary Examiner.

1. APPARATUS FOR PRODUCING METAL POWDER, WHICH COMPRISES A CONTAINER FORHOLDING MOLTEN METAL AND HAVING AN OPENING THEREIN FOR DISCHARGE OFMOLTEN METAL THEREFROM, A NOZZLE ASSEMBLY DISPOSED ADJACENT TO THECONTAINER AND HAVING A NOZZLE PROVIDED FROM AN ELONGATED SOLID BAR, SAIDNOZZLE FOR HAVING A LONGITUDINALLY ELONGATED SLOT EXTENDING THROUGH THENOZZLE BAR GENERALLY CENTRALLY OF THE LENGTH OF SAID BAR FROM ONE SIDEOF THE PERIPHERAL SURFACE OF THE NOZZLE BAR TO THE OTHER, SAID SLOTHAVING AN INLET SECTION AND AN INTERMEDIATE SECTION, AND AN OUTLETSECTION DISPOSED TOWARD THE STREAM OF MOLTEN METAL WITH THE WALLS OF THENOZZLE BAR DEFINING THE INLET SECTION BEING GENERALLY PARALLEL ANDHAVING GREATER WIDTH THEREBETWEEN THAN THE WALLS OF THE BAR DEFINING THEOUTLET SECTIONS OF THE SLOT, THE WALLS OF THE OUTLET SECTION ALSO BEINGGENERALLY PARALLEL TO EACH OTHER, AND THE WALLS OF THE BAR DEFINING THEINTERMEDIATE SECTION TAPERING FROM A GREATER WIDTH THEREBETWEEN ADJACENTTHE INLET SECTION TO A LESSER WIDTH AT THE OUTLET SECTION TO PROVIDE FORGRADUAL CONSTRICTION OF THE FLUID FLOWING THROUGH THE NOZZLE BAR TO THEOUTLET SECTION FOR DISCHARGE THEREFROM IN SHEET-LIKE FORM, LIQUID SUPPLYCONDUIT MEANS CONNECTED TO THE INLET SECTION OF THE NOZZLE BAR TO SUPPLYLIQUID TO THE INLET SECTION OF THE NOZZLE BAR UNDER SUBSTANTIALLY HIGHPRESSURE FOR FLOW THERETHROUGH AND DISCHARGE FROM THE OUTLET SECTIONAGAINST THE MOLTEN METAL TO ATOMIZE THE LATTER, MEANS ENGAGING THENOZZLE BAR TO PREVENT DEFLECTION AND LATERAL ENLARGEMENT OF THE SLOT DUETO THE INTERNAL PRESSURE OF THE LIQUID PASSING THROUGH THE SLOT, ANDMEANS TO SUPPORT THE NOZZLE ASSEMBLY ADJACENT TO THE CONTAINER.